DOCSLIB.ORG

Launchd (And Other Fun Stuff)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Launchd (And Other Fun Stuff) launchd (and other fun stuff) James Reynolds University of Utah Student Computing Labs Macintosh Support [email protected] What is launchd Jordan Hubbard’s solution /sbin/launchd One ring.., er, process to launch them all... Replacement for /sbin/init There is no init in 10.4 launchd has PID 1 and is the parent of every process Most /etc/rc’s (/etc/rc still exists for now) SystemStarter (still exists for now) mach_init.d (still exists for now) What can you do with launchd Launch Daemons (run as root) ssh, ftp, xinetd, etc... Launch Agents (run as user) Kinda like “Login Items” (“User Startup Items” in 10.3) Great example is ssh-agent Tune the kernel & environment Set limits Globally redirect stdout & stderr Much much more... Why launchd? Other solutions init required editing rc files If launch order was wrong, problems... Not the easiest thing for a newbie to configure SystemStartup was nice in theory, but... Developers guessed too often Too much requirements Too few requirements mach_init.d (bootstrap daemons) Like a horse that never got past the gate Apple used it, but few others Why launchd? launchd “Easier to manage” One location to turn stuff on and off (not really, but...) Up to now, daemons handled daemonization internally Settings were thus internal to the service Launchd can set: UID, GID, PWD, chroot, stdio, resource limits, priority Improves performance Watchdog Provides “on-demand” launches Requirements tied to sockets and file descriptors Dependencies SystemStarter had it... StartupParameters.plist & “Requires” & “Provides” Launchd has it, but very different Use IPC (inter-process communication) Either request a socket from the required service Or request a file descriptor If the service isn’t running, launchd will launch it Launchd gives your request to the service once it starts Or you can watch files or paths for changes What is “on demand”? Process only loads when it is needed Process startups only when requested Process shuts down when request is finished Frees up memory & resources Example: sshd It is only needed when port 22 is contacted So sshd only runs when something contacts port 22 Example: crond It is only needed when there is a crontab So crond only runs when there is a crontab Example: ssh-agent Only needed when opening an ssh connection Startup in 10.4 BootROM activate /System/Library/CoreServices/BootX Kernel loaded “Booting” image drawn Required kexts loaded launchd /etc/rc /System/Library/LaunchDaemons /Library/LaunchDaemons loginwindow Launchd at startup Sockets and file descriptors are registered Services should not “fork” and “daemonize” Launchd will do this for the service This is so that launchd can monitor shutdowns & more “Always on” services are started If a socket, file descriptor, or file/path is accessed The service that registered is launched If service notices no requests, it can shut down Launchd will be aware of the shutdown crond is launched this way “The Placebo Mini-Pattern” /usr/libexec/WaitingForLoginWindow Run it anytime! Reads /var/db/loginwindow.boottime Image is PART OF BINARY Search MacOSXHints for WaitingForLoginWindow for script to replace pdf Running stuff before loginwindow In 10.3 and earlier Modify loginwindow’s StartupParameters.plist In 10.4 Create /etc/rc.local If exists, this is executed by /etc/rc GUI *should* work Still testing, I’m getting strange behavior Login/logout hooks Same as before, except Do not edit /etc/ttys (unless you are using 10.2) In 10.3, you edited /Library/Preferences/com.apple.loginwindow.plist In 10.4, you edit /var/root/Library/Preferences/com.apple.loginwindow.plist BPSystemStarter says these are deprecated (pg 27) File a bug please!!!! Tech Note 301446 says how to do it sudo defaults write com.apple.loginwindow LoginHook /path/to/script Shutdown Items SystemStarter scripts had a “Shutdown” function It never worked Until 10.4... (I’ve read, not actually tested) But that is part of SystemStarter, which is going away... Launchd will call a service’s SIGTERM This is how to correctly shutdown In other words, it is up to the service Making LaunchDaemons/Agents Assuming you have a service that behaves right Edit plist files Required: Label and Program Arguments Should have OnDemand on Many many optional parameters, see: /System/Library/LaunchDaemons for examples “man launchd.plist” BPSystemStartup.pdf (from developer.apple.com) Launchd Editor http://www.codepoetry.net/products/launchdeditor So much easier, but can’t do everything DEMO Configuring launchd w/ launchctl Modify the run environment Run as sudo to change global environment This was an impossible task in 10.3 Limits “launchctl limit maxfiles 512” “limit descriptors 512” “ulimit -n 512” Logging launchctl log only error critical alert emergency This affects launchd (not sure about inheritance) Configuring launchd w/ launchctl Modify the run environment (cont) STDOUT, STDERR lsof -Pp1 launchctl stdout /var/log/launchd.out Launchd saves it’s stdout there Environment Variables launchctl setenv bla bla2 Umask launchd umask 077 More, see “launchctl help” or “man launchctl” Configuring launchd w/ launchctl Save launchctl commands /etc/launchd.conf (system settings) $HOME/.launchd.conf (user settings) Remove “launchctl” from command Example: umask 077 stdout /var/log/launchd.out stderr /var/log/launchd.err See “man launchd.conf” I was going to show ssh-agent... Anyway who has tried to use it on OS X knows it is a pain The ssh-agent binary needs a patch Couldn’t get OpenSSL 3.8.1p1 from Apple to compile There are “instructions” at www.opendarwin.org/~landonf/misc/launchd-sshagent It assumes you can compile OpenSSL It assumes you are using OpenSSL 4.0p1 10.4.1 comes with OpenSSL 3.8.1p1 I have a 3.8.1 patch file, if you can get OpenSSL to compile... Resources “man” is your friend man launchd man launchd.plist man launchctl man launchd.conf BPSystemStartup.pdf from developer.apple.com SampleD from developer.apple.com (source code) Questions.
Load more

Recommended publications
  • Introduction Use Runit with Traditional Init (Sysvinit)
    2021/07/26 19:10 (UTC) 1/12 Runit Runit Introduction runit is a UNIX init scheme with service supervision. It is a cross-platform Unix init scheme with service supervision, a replacement for sysvinit, and other init schemes and supervision that are used with the traditional init. runit is compatible with djb's daemontools. In Unix-based computer operating systems, init (short for initialization) is the first process started during booting of the computer system. Init is a daemon process that continues running until the system is shut down. Slackware comes with its own legacy init (/sbin/init) from the sysvinit package, that used to be included in almost all other major Linux distributions. The init daemon (or its replacement) is characterised by Process ID 1 (PID 1). To read on the benefits of runit, see here: http://smarden.org/runit/benefits.html * Unless otherwise stated, all commands in this article are to be run by root. Use runit with traditional init (sysvinit) runit is not provided by Slackware, but a SlackBuild is maintained on https://slackbuilds.org/. It does not have any dependencies. As we do not want yet to replace init with runit, run the slackbuild with CONFIG=no: CONFIG=no ./runit.SlackBuild Then install the resulting package and proceed as follows: mkdir /etc/runit/ /service/ cp -a /usr/doc/runit-*/etc/2 /etc/runit/ /sbin/runsvdir-start & Starting via rc.local For a typical Slackware-stlyle service, you can edit /etc/rc.d/rc.local file if [ -x /sbin/runsvdir-start ]; then /sbin/runsvdir-start & fi and then edit write /etc/rc.d/rc.local_shutdown #!/bin/sh SlackDocs - https://docs.slackware.com/ Last update: 2020/05/06 08:08 (UTC) howtos:slackware_admin:runit https://docs.slackware.com/howtos:slackware_admin:runit RUNIT=x$( /sbin/pidof runsvdir ) if [ "$RUNIT" != x ]; then kill $RUNIT fi Then give rc.local_shutdown executive permission: chmod +x /etc/rc.d/rc.local_shutdown and reboot Starting via inittab (supervised) Remove the entries in /etc/rc.d/rc.local and /etc/rc.d/rc.local_shutdown described above.
    [Show full text]
  • Mac OS X: an Introduction for Support Providers
    Mac OS X: An Introduction for Support Providers Course Information Purpose of Course Mac OS X is the next-generation Macintosh operating system, utilizing a highly robust UNIX core with a brand new simplified user experience. It is the first successful attempt to provide a fully-functional graphical user experience in such an implementation without requiring the user to know or understand UNIX. This course is designed to provide a theoretical foundation for support providers seeking to provide user support for Mac OS X. It assumes the student has performed this role for Mac OS 9, and seeks to ground the student in Mac OS X using Mac OS 9 terms and concepts. Author: Robert Dorsett, manager, AppleCare Product Training & Readiness. Module Length: 2 hours Audience: Phone support, Apple Solutions Experts, Service Providers. Prerequisites: Experience supporting Mac OS 9 Course map: Operating Systems 101 Mac OS 9 and Cooperative Multitasking Mac OS X: Pre-emptive Multitasking and Protected Memory. Mac OS X: Symmetric Multiprocessing Components of Mac OS X The Layered Approach Darwin Core Services Graphics Services Application Environments Aqua Useful Mac OS X Jargon Bundles Frameworks Umbrella Frameworks Mac OS X Installation Initialization Options Installation Options Version 1.0 Copyright © 2001 by Apple Computer, Inc. All Rights Reserved. 1 Startup Keys Mac OS X Setup Assistant Mac OS 9 and Classic Standard Directory Names Quick Answers: Where do my __________ go? More Directory Names A Word on Paths Security UNIX and security Multiple user implementation Root Old Stuff in New Terms INITs in Mac OS X Fonts FKEYs Printing from Mac OS X Disk First Aid and Drive Setup Startup Items Mac OS 9 Control Panels and Functionality mapped to Mac OS X New Stuff to Check Out Review Questions Review Answers Further Reading Change history: 3/19/01: Removed comment about UFS volumes not being selectable by Startup Disk.
    [Show full text]
  • Unit V Algorithm for Booting the UNIX System
    Unit V Algorithm for booting the UNIX system : As we’ve noted, the boot process begins when the instructions stored in the computer’s permanent, nonvolatile memory (referred to colloquially as the BIOS, ROM,NVRAM, and so on) are executed. This storage location for the initial boot instructions is generically referred to as firmware (in contrast to “software,” but reflecting the fact that the instructions constitute a program[2]). These instructions are executed automatically when the power is turned on or the system is reset, although the exact sequence of events may vary according to the values of stored parameters.[3] The firmware instructions may also begin executing in response to a command entered on the system console (as we’ll see in a bit). However they are initiated, these instructions are used to locate and start up the system’s boot program , which in turn starts the Unix operating system. The boot program is stored in a standard location on a bootable device. For a normal boot from disk, for example, the boot program might be located in block 0 of the root disk or, less commonly, in a special partition on the root disk. In the same way, the boot program may be the second file on a bootable tape or in a designated location on a remote file server in the case of a network boot of a diskless workstation. There is usually more than one bootable device on a system. The firmware program may include logic for selecting the device to boot from, often in the form of a list of potential devices to examine.
    [Show full text]
  • UCL for Freebsd
    UCL for FreeBSD A universal config language for (almost) everything in FreeBSD Allan Jude -- ScaleEngine Inc. [email protected] twitter: @allanjude Introduction Allan Jude ● 13 Years as FreeBSD Server Admin ● FreeBSD docs committer (focus: ZFS, bhyve, ucl, xo) ● Co-Author of “FreeBSD Mastery: ZFS” ● Architect of the ScaleEngine CDN (HTTP and Video) ● Host of BSDNow.tv & TechSNAP.tv Podcasts ● Extensive work with Puppet to manage our 100+ servers in 35 data centers in 12 countries ● Lots of work with ZFS to manage large collections of videos, extremely large website caches, and the pkg mirror for PCBSD Impetus At EuroBSDCon 2014 in Sofia, Jordan Hubbard ([email protected]) gave the opening keynote Among the recommendations for how FreeBSD could be improved and made easier to manage was to move away from the ‘one config file format per utility’ Jordan, being from Apple, suggested the binary XML plists used by launchd. I really didn’t want the “one true format” to be XML. Why is this a “Good Idea”™? ● Includes allow for more readable, structured, and upgradable config files ● Overlays separate the defaults from your site wide settings, and from your local settings (like defaults/rc.conf rc.conf rc.conf.local) ● Includes allow packages to install default settings (installing apache or nginx adds its log rotation to newsyslog) ● ● What is UCL ● UCL -- universal configuration language ● Inspired by bind/nginx style configuration file that all sysadmins know well ● Fully compatible with JSON, but more liberal in what it accepts, so users do
    [Show full text]
  • Beyond Init: Systemd Linux Plumbers Conference 2010
    Beyond Init: systemd Linux Plumbers Conference 2010 Kay Sievers Lennart Poettering November 2010 Kay Sievers, Lennart Poettering Beyond Init: systemd Triggers: Boot, Socket, Bus, Device, Path, Timers, More Kay Sievers, Lennart Poettering Beyond Init: systemd Kay Sievers, Lennart Poettering Beyond Init: systemd Substantial coverage of basic OS boot-up tasks, including fsck, mount, quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Kay Sievers, Lennart Poettering Beyond Init: systemd including fsck, mount, quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, Kay Sievers, Lennart Poettering Beyond Init: systemd mount, quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, including fsck, Kay Sievers, Lennart Poettering Beyond Init: systemd quota, hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, including fsck, mount, Kay Sievers, Lennart Poettering Beyond Init: systemd hwclock, readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots. Status: almost made Fedora 14. Substantial coverage of basic OS boot-up tasks, including fsck, mount, quota, Kay Sievers, Lennart Poettering Beyond Init: systemd readahead, tmpfiles, random-seed, console, static module loading, early syslog, plymouth, shutdown, kexec, SELinux, initrd+initrd-less boots.
    [Show full text]
  • UNIX System Services Z/OS Version 1 Release 7 Implementation
    Front cover UNIX System Services z/OS Version 1 Release 7 Implementation z/OS UNIX overview z/OS UNIX setup z/OS UNIX usage Paul Rogers Theodore Antoff Patrick Bruinsma Paul-Robert Hering Lutz Kühner Neil O’Connor Lívio Sousa ibm.com/redbooks International Technical Support Organization UNIX System Services z/OS Version 1 Release 7 Implementation March 2006 SG24-7035-01 Note: Before using this information and the product it supports, read the information in “Notices” on page xiii. Second Edition (March 2006) This edition applies to Version 1 Release 7 of z/OS (5637-A01), and Version 1, Release 7 of z/OS.e (5655-G52), and to all subsequent releases and modifications until otherwise indicated in new editions. © Copyright International Business Machines Corporation 2003, 2006. All rights reserved. Note to U.S. Government Users Restricted Rights -- Use, duplication or disclosure restricted by GSA ADP Schedule Contract with IBM Corp. Contents Notices . xiii Trademarks . xiv Preface . .xv The team that wrote this redbook. .xv Become a published author . xvi Comments welcome. xvii Chapter 1. UNIX overview. 1 1.1 UNIX fundamentals . 2 1.1.1 UNIX objectives . 2 1.1.2 What people like about UNIX . 2 1.1.3 What people don’t like about UNIX . 3 1.1.4 UNIX operating system . 3 1.1.5 UNIX file system . 4 1.1.6 Parameter files . 6 1.1.7 Daemons. 6 1.1.8 Accessing UNIX . 6 1.1.9 UNIX standards. 7 1.1.10 MVS and UNIX functional comparison . 8 1.2 z/OS UNIX System Services fundamentals .
    [Show full text]
  • The UNIX Time- Sharing System
    1. Introduction There have been three versions of UNIX. The earliest version (circa 1969–70) ran on the Digital Equipment Cor- poration PDP-7 and -9 computers. The second version ran on the unprotected PDP-11/20 computer. This paper describes only the PDP-11/40 and /45 [l] system since it is The UNIX Time- more modern and many of the differences between it and older UNIX systems result from redesign of features found Sharing System to be deficient or lacking. Since PDP-11 UNIX became operational in February Dennis M. Ritchie and Ken Thompson 1971, about 40 installations have been put into service; they Bell Laboratories are generally smaller than the system described here. Most of them are engaged in applications such as the preparation and formatting of patent applications and other textual material, the collection and processing of trouble data from various switching machines within the Bell System, and recording and checking telephone service orders. Our own installation is used mainly for research in operating sys- tems, languages, computer networks, and other topics in computer science, and also for document preparation. UNIX is a general-purpose, multi-user, interactive Perhaps the most important achievement of UNIX is to operating system for the Digital Equipment Corpora- demonstrate that a powerful operating system for interac- tion PDP-11/40 and 11/45 computers. It offers a number tive use need not be expensive either in equipment or in of features seldom found even in larger operating sys- human effort: UNIX can run on hardware costing as little as tems, including: (1) a hierarchical file system incorpo- $40,000, and less than two man years were spent on the rating demountable volumes; (2) compatible file, device, main system software.
    [Show full text]
  • How to Boot Linux in One Second …Why Userland Is a Waste of Time ;)
    How to boot Linux in one second …why userland is a waste of time ;) Jan Altenberg Linutronix GmbH Jan Altenberg Linutronix GmbH 1 from zero… Jan Altenberg Linutronix GmbH 2 to hero… Jan Altenberg Linutronix GmbH 3 Overview 1. Basics Motivation Some technical basics 2. Optimizations Bootloader Kernel Filesystem Application 3. Example Optimizing an ARMv5 based device Optimizing the test system Jan Altenberg Linutronix GmbH 4 Motivation 1. Basics Motivation Some technical basics 2. Optimizations Bootloader Kernel Filesystem Application 3. Example Optimizing an ARMv5 based device Optimizing the test system Jan Altenberg Linutronix GmbH 5 • solution: power-off instead of suspending • BUT: Users are not used to wait Motivation Motivation ''marketing'' automotive applications energy saving Jan Altenberg Linutronix GmbH 6 • BUT: Users are not used to wait Motivation Motivation ''marketing'' automotive applications energy saving • solution: power-off instead of suspending Jan Altenberg Linutronix GmbH 6 Motivation Motivation ''marketing'' automotive applications energy saving • solution: power-off instead of suspending • BUT: Users are not used to wait Jan Altenberg Linutronix GmbH 6 Some technical basics 1. Basics Motivation Some technical basics 2. Optimizations Bootloader Kernel Filesystem Application 3. Example Optimizing an ARMv5 based device Optimizing the test system Jan Altenberg Linutronix GmbH 7 Some technical basics First step: Define your requirements!!!! What's the limit for the boot time? Which functionality should be available? Speed
    [Show full text]
  • Linux Kernel Initialization
    Bootlin legacy Linux kernel training materials Linux kernel initialization This file is an old chapter of Bootlin’ embedded Linux kernel and driver development training materials (https://bootlin.com/training/kernel/), which has been removed and is no longer maintained. PDF version and sources are available on https://bootlin.com/doc/legacy/kernel-init/ - Kernel, drivers and embedded Linux - Development, consulting, training and support - https://bootlin.com 1/1 Rights to copy © Copyright 2004-2018, Bootlin License: Creative Commons Attribution - Share Alike 3.0 http://creativecommons.org/licenses/by-sa/3.0/legalcode You are free: I to copy, distribute, display, and perform the work I to make derivative works I to make commercial use of the work Under the following conditions: I Attribution. You must give the original author credit. I Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one. I For any reuse or distribution, you must make clear to others the license terms of this work. I Any of these conditions can be waived if you get permission from the copyright holder. Your fair use and other rights are in no way affected by the above. - Kernel, drivers and embedded Linux - Development, consulting, training and support - https://bootlin.com 2/1 From Bootloader to user space - Kernel, drivers and embedded Linux - Development, consulting, training and support - https://bootlin.com 3/1 Kernel Bootstrap (1) How the kernel bootstraps itself appears in kernel building. Example on ARM (pxa cpu) in Linux 2.6.36: ..
    [Show full text]
  • 27Th Large Installation System Administration Conference
    FEBRUARY 2014 vOL. 39, NO. 1 Conference Reports ELECTRONIC SUPPLEMENT 27th Large Installation System Administration maintains the university email systems, DNS, and load balanc- Conference ers, he is also active both on IRC and many mailing lists, such Washington, D.C. as lopsa-discus, bind-users, and several FreeBSD lists. Chen November 3-8, 2013 often provides not only answers to questions, but also frequently includes examples based on his own experience. Summarized by Jonathon Anderson, Ben Cotton, John Dennert, Rik Farrow, Andrew Hoblitz, David Klann, Thomas Knauth, Georgios Larkou, Cory Lueninghoener, Scott Murphy, Tim Nelson, Carolyn Rowland , Keynote Summarized by Thomas Knauth ([email protected]) Josh Simon, and Steve VanDevender Modern Infrastructure: The Convergence of Network, Wednesday, November 6, 2013 Compute, and Data Opening Remarks and Awards Jason Hoffman, Founder, Joyent Summarized by Rik Farrow ([email protected]) Jason started the talk by naming the three main producers of The LISA co-chairs, Narayan Desai, Argonne National Labora- information: nature, humans, and machines. The information tory, and Kent Skaar, VMware, opened the conference by telling produced by nature far outweighs that of either machines (e.g., us that there had been 76 invited talks proposals, of which 33 servers, sensors, cars) or humans (e.g., pictures, photos, emails). were accepted. To fit these in, the co-chairs changed the Invited For example, to sample a single person’s genome will generate 20 Talks format so that most sessions were composed of two talks. I TB of data. was skeptical, as were some others, but the talks actually turned out well, with an excellent set of IT tracks.
    [Show full text]
  • Auditing and Exploiting Apple IPC Ianbeer
    Auditing and Exploiting Apple IPC ianbeer Jailbreak Security Summit May 2015 About me: ● Security Researcher with Project Zero ● Won pwn4fun last year with a JavaScriptCore bug and some kernel bugs ● That macbook air now runs ubuntu :) ● Over the last year reported ~60 OS X sandbox escapes/priv-escs (10 still unpatched) ● Some accidentally also present on iOS This talk: ● Overview of (almost) all IPC mechanisms on iOS/OS X ● Quick look at Mach Message fundamentals ● Deep-dive into XPC services ● Exploiting XPC bugs ● fontd IPC and exploiting fontd bugs ● Mitigations and the future socketpair semaphores AppleEvents IPC Zoo signals domain sockets fifo shmem Pasteboard CFMessage Distributed NSXPC A B Port Notifications D CFPort MIG XPC O Mach Messages XNU Why care about IPC? Sandboxing You probably get initial code execution in some kind of sandbox in userspace… ● renderer/plugin process ● quicklook-satellite ● ntpd Plenty of stuff is still unsandboxed on OS X ● appstore app though (...Adobe Reader...) Sandbox escape models Privilege separation: Two parts of the same application work together to isolate dangerous code Untrusted helper Trusted “broker” IPC Sandboxed Unsandboxed Sandbox escape models Privilege separation: Two parts of the same application work together to isolate dangerous code Chrome PPAPI Plugin Browser IPC Sandboxed Unsandboxed Sandbox escape models Privilege separation: Two parts of the same application work together to isolate dangerous code WebContent WebKit2/Safari IPC Sandboxed Unsandboxed Sandbox escape models Privilege
    [Show full text]
  • Linux Internals
    LINUX INTERNALS Peter Chubb and Etienne Le Sueur [email protected] A LITTLE BIT OF HISTORY • Ken Thompson and Dennis Ritchie in 1967–70 • USG and BSD • John Lions 1976–95 • Andrew Tanenbaum 1987 • Linux Torvalds 1991 NICTA Copyright c 2011 From Imagination to Impact 2 The history of UNIX-like operating systems is a history of people being dissatisfied with what they have and wanting to do some- thing better. It started when Ken Thompson got bored with MUL- TICS and wanted to write a computer game (Space Travel). He found a disused PDP-7, and wrote an interactive operating sys- tem to run his game. The main contribution at this point was the simple file-system abstraction. (Ritchie 1984) Other people found it interesting enough to want to port it to other systems, which led to the first major rewrite — from assembly to C. In some ways UNIX was the first successfully portable OS. After Ritchie & Thompson (1974) was published, AT&T became aware of a growing market for UNIX. They wanted to discourage it: it was common for AT&T salesmen to say, ‘Here’s what you get: A whole lot of tapes, and an invoice for $10 000’. Fortunately educational licences were (almost) free, and universities around the world took up UNIX as the basis for teaching and research. The University of California at Berkeley was one of those univer- NICTA Copyright c 2011 From Imagination to Impact 2-1 sities. In 1977, Bill Joy (a postgrad) put together and released the first Berkeley Software Distribution — in this instance, the main additions were a pascal compiler and Bill Joy’s ex editor.
    [Show full text]